Although intravenous drug users (IVDU) are rapidly becoming a major group at risk for AIDS, little is known regarding potential modes of transmission and infection different from those of the better-studied homosexual/bisexual male groups. Because of the severely inflamed and diseased oral and dental tissues characteristic of most IVDU, transmission of HIV via the oral cavity may be an important clinical problem, especially in the light of the extensive practice of oral sex in this population. In addition, it is desirable to have a sensitive, simple, safe, non-invasive method to assess the HIV-status of large groups of individuals, such as IVDU, in which there are particular problems of cooperation, agreeability, and sensitivity. The longterm objectives of this subproject are to determine whether there is a greater potential for the oral transmission of AIDS by HIV-seropositive male and female IVDU than was observed in a previously studied cohort of homosexual/bisexual men, and to refine a non-invasive diagnostic method for HIV detection from oral crevicular fluids. Therefore, the correlation between levels of HIV in serum and whole saliva of 400 infected IVDU will be determined by quantitating the p24 core protein characteristic of this retrovirus; the in vitro infectivities of HIV derived from serum and whole saliva of the same IVDU will be evaluated by cocultivation with peripheral blood mononuclear cells (PBMC) from seronegative donors; and the assessment of HIV-status using a nucleic acid hybridization technique for detecting proviral DNA in oral crevicular fluid collected on paper points will be compared with that determined by more conventional, invasive serological techniques. This information, along with the data from the other related subprojects, may be useful in formulating strategies to prevent, contain, and treat HIV infection in IVDU.